Finding Feature Information

Your software release may not support all the features documented in this module. For the latest caveats and feature information, see
Bug Search Tool and the release notes for your platform and software release. To find information about the features documented in this module, and to see a list of the releases in which each feature is supported, see the feature information table at the end of this module.

Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to
www.cisco.com/​go/​cfn. An account on Cisco.com is not required.

Restrictions for cGVRP

A non-Cisco device can only interoperate with a Cisco device through .1Q trunks.

VLAN Mapping is not supported with GVRP.

cGVRP and Connectivity Fault Management (CFM) can coexist but if the line card (LC) or supervisor does not have enough mac-match registers to support both protocols, the cGVRP ports on those LCs are put in error disabled state. To use Layer 2 functionality, disable cGVRP on those ports and configure shut/no shut.

Native VLAN Tagging causes frames sent to the native VLAN of the .1Q trunk ports to be encapsulated with .1Q tags. Problems may arise with other GVRP participants on the LAN because they may not be able to admit tagged GVRP PDUs. Caution must be exercised if both features are enabled at the same time.

802.1X authentication and authorization takes place after the port becomes link-up and before the Dynamic Trunking Protocol (DTP) negotiations start prior to GVRP running on the port.

Port Security works independently from GVRP and it may be limited to the number of other GVRP participants on a LAN that a GVRP enabled port on a device can communicate with.

GVRPs cannot be configured and used on a sub-interface.

GVRP and UniDirectional Link Routing (UDLR) should not be enabled on the same interface because UDLR limits frames in one direction on the port and GVRP is a two way communication protocol.

Additional memory is required to store GARP/GVRP configurations and states per GVRP enabled port, but it can be dynamically allocated on demand.

GARP Multicast Registration Protocol (GMRP) is not supported.

Information About cGVRP

GARP GVRP Definition

GVRP enables automatic configuration of switches in a VLAN network allowing network devices to dynamically exchange VLAN configuration information with other devices. GVRP is based on GARP which defines procedures for registering and deregistering attributes with each other. It eliminates unnecessary network traffic by preventing attempts to transmit information to unregistered users.

GVRP is defined in IEEE 802.1Q.

cGVRP Overview

GVRP is a protocol that requires extensive CPU time in order to transmit all 4094 VLAN states on a port. In Compact mode only one PDU is sent and it includes the states of all the 4094 VLANs on a port.

VLAN pruning can be accomplished faster by running in a special mode, Fast Compact Mode, and on point-to-point links.

In Compact GVRP a GVRP PDU may be sent out the port if the port is in forwarding state in a spanning tree instance. GVRP PDUs must be transmitted in the native VLAN of .1Q trunks.

GVRP Interoperability with VTP and VTP Pruning

VTP Pruning is an extension of VTP. It has its own Join message that can be exchanged with VTP PDUs. VTP PDUs can be transmitted on both .1Q trunks and ISL trunks. A VTP capable device is in either one of the three VTP modes: Server, Client, or Transparent.

When VTP Pruning and GVRP are both enabled globally, VTP Pruning is run on ISL trunks, and GVRP is run on .1Q trunks.

Compact GVRP has two modes: Slow Compact Mode, and Fast Compact Mode. A port can be in Fast Compact Mode if it has one GVRP enabled peer on the same LAN segment, and the peer is capable of operating in Compact Mode. A port is in Slow Compact Mode if there are multiple GVRP participants on the same LAN segment operating in Compact Mode.

GVRP Interoperability with Other Software Features and Protocols

This section briefly describes GVRP interoperability with the following software features and protocols.

STP

Spanning Tree Protocol (STP) may run in one of the three STP modes: Multiple Spanning Tree(MST), Per VLAN Spanning Tree (PVST), or Rapid PVST. An STP mode range causes the forwarding ports to leave the forwarding state as STP has to reconverge. This may cause GVRP to have its own topology change as Join messages my be received on some new ports and Leave timers may expire on some others.

DTP

DTP (DDSN Transfer Protocol) negotiates the port mode (trunk versus non-trunk) and the trunk encapsulation type between two DTP enabled ports. After negotiation DTP may set the port to either ISL trunk, or .1Q trunk, or non-trunk. DTP negotiation occurs after ports become link-up and before they become forwarding in spanning trees. If GVRP is administratively enabled on a port and the device, it should be initialized after the port is negotiated to be a .1Q trunk.

VTP

VTP (Virtual Terminal Protocol) version 3 expands the range of VLANs that can be created and removed via VTP. VTP Pruning is available for VLAN 1 through 1005 only.

EtherChannel

When multiple .1Q trunk ports are grouped by either Port Aggregation Protocol (PAgP) or Link Aggregation Control Protocol (LACP) to become an EtherChannel, the EtherChannel can be configured as a GVRP participant. The physical ports in the EtherChannel cannot be GVRP participants by themselves. Since an EtherChannel is treated like one virtual port by STP, the GVRP application can learn the STP state change of the EtherChannel just like any physical port. The EtherChannel, not the physical ports in the channel, constitutes the GARP Information Propagation (GIP) context.

High Availability

High Availability (HA) is a redundancy feature in IOS. On platforms that support HA and State SwitchOver (SSO), many features and protocols my resume working in a couple of seconds after the system encounters a failure such as a crash of the active supervisor in a Catalyst 7600 switch. GVRP needs to be configured to enable user configurations, and protocol states should be synched to a standby system. If there is a failure of the active system, the GVRP in the standby system which now becomes active, has all the up-to-date VLAN registration information.

Enter the timer-value. The timer-value range is between 200 and 2147483647.

Step 5

gvrpregistrationnormal

Example:

Router(config)# gvrp registration normal

Sets the registrar for normal response to incoming GVRP messages.

Step 6

end

Example:

Router(config)# end

Exits interface configuration mode.

Disabling mac-learning on VLANs

To disable mac-learning on VLANs, complete the following steps.

SUMMARY STEPS

1.enable

2.configureterminal

3.gvrpmac-learningauto

4.end

DETAILED STEPS

Command or Action

Purpose

Step 1

enable

Example:

Router> enable

Enables privileged EXEC mode.

Enter your password if prompted.

Step 2

configureterminal

Example:

Router# configure terminal

Enters global configuration mode.

Step 3

gvrpmac-learningauto

Example:

Router(config)# gvrp mac-learning auto

Disables learning of mac-entries.

Step 4

end

Example:

Router(config)# end

Exits global configuration mode.

Enabling a Dynamic VLAN

To enable a dynamic VLAN, complete the following steps.

SUMMARY STEPS

1.enable

2.configureterminal

3.gvrpvlancreate

4.end

DETAILED STEPS

Command or Action

Purpose

Step 1

enable

Example:

Router> enable

Enables privileged EXEC mode.

Enter your password if prompted.

Step 2

configureterminal

Example:

Router# configure terminal

Enters global configuration mode.

Step 3

gvrpvlancreate

Example:

Router(config)# gvrp vlan create

Enables a dynamic VLAN when cGRVP is configured.

Step 4

end

Example:

Router(config)# end

Exits global configuration mode.

Troubleshooting the cGVRP Configuration

To troubleshoot the cGVRP configuration, use one or more of the commands listed below.

Use the showgvrpsummarycommand and the showgvrpinterfacecommand to display configuration information and interface state information. Use the debuggvrp command to enable all or a limited set of output messages related to an interface.

Verifying CE Ports Configured as ISL Ports Example

The following is sample output of the showrunning-configinterface command, the showgrvpsummary,the showgrvpinterfacecommand, and the showvlansummary command. In this configuration the CE ports are configured as ISL ports.

RFCs

No new or modified RFCs are supported by this feature, and support for existing standards has not been modified by this feature.

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Feature Information for cGVRP

The following table provides release information about the feature or features described in this module. This table lists only the software release that introduced support for a given feature in a given software release train. Unless noted otherwise, subsequent releases of that software release train also support that feature.

Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to
www.cisco.com/​go/​cfn. An account on Cisco.com is not required.

Table 1 Feature Information for cGVRP

Feature Name

Releases

Feature Information

cGVRP

12.2(33)SRB

The Compact (c) Generic Attribute Registration Protocol (GARP) VLAN Registration Protocol (GVRP) feature reduces CPU time for transmittal of 4094 VLAN states on a port. GVRP enables automatic configuration of switches in a VLAN network allowing network devices to dynamically exchange VLAN configuration information with other devices. GVRP is based on GARP which defines procedures for registering and deregistering attributes with each other. It eliminates unnecessary network traffic by preventing attempts to transmit information to unregistered users.

GVRP is defined in IEEE 802.1Q.

The following commands were introduced or modified:
cleargvrpstatistics,debuggvrp,gvrpglobal,gvrpmac-learning,gvrpregistration,gvrptimer,gvrpvlancreate,showgvrpinterface,showgvrpsummary.